Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page

# Why do i get different values for total heat gain energy or heat loss energy for different window to wall ratio values but for the same building geometry [closed]

I calculated WWR using different approaches which gave me different values for WWR.

The zone heating values oor heat gain and heat loss are around 1.210^8 J for WWR ~ 9 % but 3.510^8 J for WWR ~35 %. How can there be different heat data and graphs for the same weather and same building gemometry.

edit retag reopen merge delete

### Closed for the following reason duplicate question by David Goldwasser close date 2016-11-28 10:49:01.797435

Seems like a duplicate of this post

( 2016-11-26 19:28:16 -0500 )edit

Sort by ยป oldest newest most voted

The values of WWR is different when calculated manually by taking the ratio of surface area of window and walls as compared to the WWR values of the building envelope calculated by the open studio simulation results. I dont know why? Kindly help

more

Glazing or glass have a SHGC factor, which merely describes about the solar gain by the window. The more the Glazing area and the more the radiation upon it, the more is the solar infiltration. If the window have a very high SHGC then it will have very high incoming solar radiation. The more the higher the Solar heat gain coefficient (SHGC), the more solar radiation is able to pass through the glass. If the window area is high then there is direct formula Q= SHGC X Area, where Q is the heat infiltration. So whether the are or SHGC is high depending upon the climate the heat gains are different.

more

Changing the WWR changes the construction makeup of different parts of the geometry, so it isn't really the same. It also affects solar gain entering the building through translucent fenestration.

more

I agree with David. Furthermore, the distribution of windows on different facades will also affect your result. If i understand the question right, you should by no means expect the same answer from different WWRs.

( 2016-11-24 05:21:23 -0500 )edit

## Stats

Asked: 2016-11-22 18:17:08 -0500

Seen: 367 times

Last updated: Nov 25 '16